Products such as food and personal care items are provided in packages that provide for access. The packages protect the product from damage during shipping and handling; seal the product to prevent the product from deterioration due to environmental conditions for predetermined periods of time and as a storage vessel. Once opened, while most containers can be reclosed, the effectiveness of the closing arrangement varies widely.
A typical film bag is made from a laminate that includes an outer film layer adhesively secured to an inner sealing layer. The outer layer is usually made from a material that facilitates printing. The inner layer is usually made from a material that enables the package to be sealed. Other layers can also be incorporated. Properties, such as permeability to oxygen and moisture, strength, stiffness and other packaging requirements may dictate material selection. The outer and inner layers are both typically made from plastic film, such as polyethylene or polypropylene.
Some packaging can be reclosed after opening by folding the end over or by rolling the end down. When sufficient material is available, the packaging may be reclosed with a twist tie, a wire or wire-like length of material twisted around excess packaging. This method for sealing the contents of the packaging makes it more likely that the contents of the packaging are exposed to environmental conditions that accelerate deterioration.
Various methods of preventing the conventional bag from reopening have been attempted. Household items such as clothes pins or paper clips have been used to hold the conventional bag closed. In addition, clips have been specially designed and manufactured as closures for bags.
Other attempts to provide a closure mechanism for a conventional bag have tried to provide a closure device with the bag itself. Some bags have been provided with a metal wire or strip along the length of the bag, the wire or strip being easily bent under the user's manipulation, but resisting the tendency of the bag to open once folded, thus keeping the bag closed. Other bags are provided with nonresilient flexible strips disposed transversely to the length of the bag. The nonresilient strip is along the top of the bag and extends beyond the side of the bag. Once the top of the bag is rolled down a first side, the extending portion of the strip is folded snugly against a second side, opposite the first side, preventing the bag from unrolling.
Recently, re-sealable food containers have been developed that include strips of pressure sensitive adhesive tape adhered to the outside of the roll stock. This pressure sensitive adhesive tape provides a mechanism to allow the bag to be folded or rolled down and make contact with the pressure sensitive adhesive tape creating a closure. Alternatively, when the bag is closed and folded downwardly, the portion with releasable adhesive may be attached to the folded portion, thereby preventing the bag from unrolling. One problem with a retrofitted closure tab is the expense of manufacturing and handling the tab.
An additional re-sealable container is disclosed in U.S. Pat. No. 7,416,768. The package has an inner layer and an outer layer which are laminated together. The outer layer of the packaging film is cut completely through, so that a strip of the outer layer is no longer connected to the rest of the layer. By adjusting the bond between the outer layer and the inner layer, the strip can be peeled away from the rest of the film without injuring the barrier layer that is part of the inner loop. The adhesive layer concealed beneath the removable strip can serve as a closure for a partially full bag.
Further improvements in re-sealable food packages that improve the durability, effectiveness and repeatability of the resealable package are desired.